Lens holding tool and lens holding method

ABSTRACT

A lens holding tool for holding a plurality of lenses as a workpiece in a grinding or polishing process includes: a base portion; and a plurality of lens receiving portions respectively provided at a plurality of positions on a surface of the base portion so as to protrude from the surface. Each of the plurality of lens receiving port has a lens receiving face configured to be in contact with at least a part of a support surface which is an end face of each of the plurality of lenses, and an outer circumference of the lens receiving face is positioned higher than the surface of the base portion.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of PCT international application Ser.No. PCT/JP2014/062347 filed on May 8, 2014 which designates the UnitedStates, incorporated herein by reference, and which claims the benefitof priority from Japanese Patent Application No. 2013-227598, filed onOct. 31, 2013, incorporated herein by reference.

BACKGROUND

1. Technical Field

The disclosure relates to a lens holding tool and method for holdinglenses in a grinding or polishing process of the lenses.

2. Related Art

As a method for performing a grinding or polishing process on an endface of a plurality of lenses at the same time, a method using arecessed plate is known (for example, see Japanese Laid-open PatentPublication No. 2-152760, Japanese Laid-open Patent Publication No7-136915, Japanese Laid-open Patent Publication No. 2001-9692, andJapanese Laid-open Patent Publication No. 2003-103444). The recessedplate is a lens holding tool where a plurality of counterbore holes(hereinafter referred to as countersinks) for holding lenses is formedon a surface of a spherically-shaped base material. In a lens processingmethod using the recessed plate, each countersink is caused to hold alens as a workpiece and a processing tool, such as a grindstone, onwhich a spherical processing surface having a desired curvature isformed, is caused to come into contact with these lenses and is rotated.Thereby, it is possible to collectively grind or polish end faces of aplurality of lenses into spherical surfaces having the same curvature.Further, when the recessed plate is used, it is possible to performprocessing in a more stable manner than a case in which lenses areprocessed one by one, so that there is an advantage that the processingaccuracy is improved.

SUMMARY

In some embodiments, a lens holding tool for holding a plurality oflenses as a workpiece in a grinding or polishing process includes: abase portion; and a plurality of lens receiving portions respectivelyprovided at a plurality of positions on a surface of the base portion soas to protrude from the surface. Each of the plurality of lens receivingportions has a lens receiving face configured to be in contact with atleast a part of a support surface which is an end face of each of theplurality of lenses, and an outer circumference of the lens receivingface is positioned higher than the surface of the base portion.

In some embodiments, a method for causing a lens holding tool to hold aplurality of lenses as a workpiece in a grinding or polishing process isprovided. The lens holding tool has a base portion and a plurality oflens receiving portions on the base portion. Each of the plurality oflens receiving portions has a lens receiving face. The method includes:applying an adhesive to at least one of the lens receiving face and asupport surface which is an end face of each of the plurality of lenses;placing each of the plurality of lenses on the lens receiving face tocause the support surface and the lens receiving face to be in contactwith each other through the adhesive; positioning each of the pluralityof lenses with respect to each of the lens receiving portions; andcuring the adhesive. Each of the lens receiving portions protrudes froma surface of the base portion, and an outer circumference of the lensreceiving face is positioned higher than the surface of the baseportion.

The above and other features, advantages and technical and industrialsignificance of this invention will be better understood by reading thefollowing detailed description of presently preferred embodiments of theinvention, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic diagrams illustrating a structure of alens holding tool according to a first embodiment of the presentinvention;

FIG. 2 is an enlarged cross-sectional view illustrating a lens receivingportion illustrated in FIGS. 1A and 1B;

FIG. 3 is a perspective view illustrating a ring that is supplementarilyused when causing the lens receiving portion illustrated in FIGS. 1A and1B to hold a lens;

FIG. 4 is a cross-sectional view for explaining an adhesive applicationstep, a lens placement step, and a positioning step of a lens holdingmethod according to the first embodiment of the present invention;

FIG. 5 is a cross-sectional view for explaining the positioning step ofthe lens holding method according to the first embodiment of the presentinvention;

FIG. 6 is a cross-sectional view illustrating a structure of a lensholding tool according to a modified example 1-1 of the first embodimentof the present invention;

FIG. 7 is a cross-sectional view illustrating a structure of a lensholding tool according to a modified example 1-2 of the first embodimentof the present invention;

FIG. 8 is a cross-sectional view illustrating a structure of a lensholding tool according to a second embodiment of the present invention;

FIG. 9 is a cross-sectional view for explaining a positioning step of alens holding method according to the second embodiment of the presentinvention;

FIG. 10 is a diagram illustrating a structure of a lens holding toolaccording to a third embodiment of the present invention;

FIG. 11 is a diagram for explaining a positioning step of a lens holdingmethod according to the third embodiment of the present invention;

FIG. 12 is a diagram illustrating a structure of a lens holding toolaccording to a fourth embodiment of the present invention;

FIG. 13 is a diagram for explaining a positioning step of a lens holdingmethod according to the fourth embodiment of the present invention;

FIG. 14 is a cross-sectional view illustrating a structure of a lensholding tool according to a fifth embodiment of the present invention;

FIG. 15 is a partial cross-sectional view illustrating a lens receivingportion illustrated in FIG. 14;

FIG. 16 is a partial cross-sectional view for explaining an adhesiveapplication step, a lens placement step, and a positioning step of alens holding method according to the fifth embodiment of the presentinvention;

FIG. 17 is a partial cross-sectional view for explaining a lensreceiving portion attaching step of the lens holding method according tothe fifth embodiment of the present invention; and

FIG. 18 is a cross-sectional view illustrating a structure of a lensreceiving portion according to a modified example 5-1 of the fifthembodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, embodiments of a lens holding tool and a lens holdingmethod according to the present invention will be described withreference to the drawings. The present invention is not limited by theembodiments. The same reference signs are used to designate the sameelements throughout the drawings. The drawings are schematic and sizerelationships and ratios of portions are different from actual ones.Also, size relationships and ratios of portions between the drawings maybe different from each other.

First Embodiment

FIGS. 1A and 1B are schematic diagrams illustrating a structure of alens holding tool according to a first embodiment of the presentinvention. FIG. 1A is a top view illustrating a state in which aplurality of lenses as a workpiece is held by the lens holding tool.FIG. 1B is an A-A cross-sectional view of FIG. 1A. As illustrated inFIGS. 1A and 1B, the lens holding tool 100 according to the firstembodiment of the present invention includes a base portion 101 having ashaft portion 102 and a plurality of lens receiving portions 104 whichis provided so as to protrude from a surface 103 of the base portion101. A plurality of lenses 10 as a workpiece is held by the lensreceiving portions 104, respectively, through adhesives 112. AlthoughFIG. 1A illustrates an example in which seven lens receiving portions104 are provided, the number of the lens receiving portions 104 only hasto be three or more. These lens receiving portions 104 are arranged soas to be rotationally symmetrical on the surface of the base portion101.

The base portion 101 is a member made of metal or alloy, and forms apart of a spherical body. The surface 103 of the base portion 101 has aconvex spherical shape. The shaft portion 102 is provided on a surfaceopposite to the surface 103 on the same axis as that of the rotationcenter of the base portion 101.

FIG. 2 is an enlarged cross-sectional view illustrating the lensreceiving portion 104. The lens receiving portion 104 has a cylindricalshape whose outer diameter is substantially the same as an outerdiameter D1 of the lens 10. The lens receiving portion 104 is providedso that a rotation symmetry axis R1 of the cylinder is perpendicular toa surface in contact with the same spherical surface 103′ as the surface103 at a position of the rotation symmetry axis R1.

A lens receiving face 105, which is an upper end face of the lensreceiving portion 104, is in contact with a support surface 12, which isan end face opposite to a process surface 11 of the lens 10, andsupports the lens 10. In the first embodiment, corresponding to thesupport surface 12 of the convex spherical shape, the lens receivingface 105 has a concave spherical shape which has a spherical center onthe rotation symmetry axis R1 and whose curvature radius issubstantially the same as that of the support surface 12.

The shape of the lens receiving face 105 is not limited to the concavespherical shape. For example, when the support surface 12 has a concavespherical shape, the lens receiving face 105 may have a convex sphericalshape corresponding to the shape of the support surface 12.Alternatively, when the support surface 12 has a planar shape, the lensreceiving face 105 may have a planar shape.

The height of an outer circumference 106 of the lens receiving face 105is higher than that of the surface 103 of the base portion 101. Thereby,it is possible to prevent a processing tool such as a grindstone frombeing in contact with the surface 103 of the base portion 101 duringprocessing of the lens 10, regardless of the thickness of an edgeportion (a flange portion) of the lens 10. The height of an innercircumference 107 of the lens receiving face 105 as seen from thesurface 103 of the base portion 101 is determined by the height of theouter circumference 106, the curvature radius of the lens receiving face105, and the width of the lens receiving portion 104 in the radialdirection. Therefore, the inner circumference 107 may be lower than thesurface 103 of the base portion 101.

An opening 108 inside the lens receiving portion 104 is dug such thatthe lens 10 does not contact with the base portion 101 according to thecurvature radius of the support surface 12 of the lens 10. The positionof a bottom surface of the opening 108 may be lower than the surface 103of the base portion 101.

Next, a lens holding method and a lens processing method according tothe first embodiment of the present invention will be described withreference to FIGS. 3 to 5.

FIG. 3 is a perspective view illustrating a ring 110 that issupplementarily used when causing the lens receiving portion 104 to holdthe lens 10. As illustrated in FIG. 3, the ring 110 is a cylindricalmember whose inner diameter D2 is substantially the same as the outerdiameter of the lens receiving portion 104 (that is, the outer diameterD1 of the lens 10). The ring 110 can be attached to and detached from(fitted into) the lens receiving portion 104. The ring 110 is fittedinto the lens receiving portion 104 so that a positioning surface of thelens 10, which is in parallel with the rotation symmetry axis R1 (seeFIG. 2) of the lens receiving portion 104 and whose distances from therotation symmetry axis R1 are the same, is formed around the lensreceiving portion 104 by an inner circumferential surface 111 of thering 110.

FIG. 4 is a cross-sectional view for explaining an adhesive applicationstep, a lens placement step, and a positioning step of the lens holdingmethod according to the first embodiment. FIG. 5 is a cross-sectionalview for explaining the positioning step.

When causing each of the lens receiving portions 104 to hold the lens10, first, as illustrated in FIG. 4, the adhesive 112, such as wax orultraviolet curing resin, is applied to the lens receiving face 105. Theadhesive 112 may be applied to the support surface 12 of the lens 10 ormay be applied to both the support surface 12 and the lens receivingface 105.

Subsequently, the lens 10 is placed on the lens receiving face 105 withthe support surface 12 of the lens 10 facing the lens receiving face105, and the support surface 12 of the lens 10 and the lens receivingface 105 are caused to be in contact with each other through theadhesive 112. In this case, it is preferable to adjust the position ofthe lens 10 such that the outer circumference of the lens 10 and theouter circumference of the lens receiving portion 104 are substantiallycoincident with each other.

Subsequently, the ring 110 is fitted into the lens receiving portion 104by putting the ring 110 from above the lens 10, and the outercircumferential surface of the lens 10 and the outer circumferentialsurface of the lens receiving portion 104 are caused to be in contactwith the inner circumferential surface 111 of the ring 110. Thereby, asillustrated in FIG. 5, a state in which the lens 10 is positioned withrespect to the lens receiving portion 104 is maintained.

Next, the adhesive 112 is cured. For example, when the wax is used asthe adhesive 112, the adhesive 112 is cured by cooling. When theultraviolet curing resin is used as the adhesive 112, the adhesive 112is cured by irradiating the adhesive 112 with ultraviolet rays throughthe lens 10. Thereby, the lens 10 is held in a state in which the lens10 is positioned with respect to the lens receiving portion 104. Afterthe adhesive 112 is cured, the ring 110 is removed.

The operations as described above are performed on each of the lensreceiving portions 104 provided in the lens holding tool 100, so thatthe lens 10 is held by all the lens receiving portions 104 (see FIGS. 1Aand 1B).

Subsequently, the lens holding tool 100 is attached to a lens processingdevice (not illustrated in the drawings) so that the shaft portion 102is rotatable. Then, a processing tool, where a processing surface havinga spherical shape (for example, a concave spherical shape) with adesired curvature is formed, is caused to be in contact with the processsurface 11 of the lens 10, and the processing tool is rotated. Thereby,the process surface 11 of each lens 10 is polished or ground into aspherical shape (for example, a convex spherical shape) corresponding tothe shape of the processing surface.

After the processing of the lens 10 is completed, the lens 10 isdetached from the lens receiving portion 104 by dissolving the adhesive112 by using organic solvent or the like. Thereby, it is possible toobtain simultaneously a plurality of lenses 10 where the process surface11 is polished into a spherical shape having the same curvature.

As described above, according to the first embodiment, the lensreceiving portion 104 is provided so that the lens receiving portion 104protrudes from the surface 103 of the base portion 101, and the lens 10is held by the lens receiving face 105 of the lens receiving portion104. Consequently, it is possible to process the lens 10 by holding thelens 10 in the lens holding tool 100, regardless of the thickness of theedge portion of the lens 10.

Further, according to the first embodiment, the positioning of the lens10 is performed by fitting the ring 110 to the lens receiving portion104, and the adhesive 112 is cured in this state. Consequently, it ispossible to fix the lens 10 at an appropriate position in the lensreceiving portion 104. Therefore, even when the edge portion of the lens10 is thin, it is possible to cause the lens receiving portion 104 tohold the lens 10 without generating positional shift.

Further, according to the first embodiment, the lens receiving portion104 is formed into a cylindrical shape, and the lens receiving face 105is caused to be in contact with a part of the support surface 12 of thelens 10. Consequently, it is possible to reduce distortion generatedwhen the lens 10 adheres to the lens receiving face 105.

In the first embodiment, the surface 103 of the base portion 101 isformed into a convex spherical shape so that a plurality of lensreceiving faces 105 is arranged in a convex shape in order to grind orpolish the process surface 11 of the lens 10 into a convex sphericalshape. However, when grinding or polishing the process surface 11 of thelens 10 into a concave spherical shape, it is preferable to form thesurface 103 of the base portion 101 into a concave spherical shape sothat a plurality of the lens receiving faces 105 is arranged in aconcave shape. Further, when a plurality of the lens receiving faces 105is arranged corresponding to a processed shape (the curvature) of theprocess surface 11, the shape of the surface 103 of the base portion 101is not particularly limited and need not necessarily be a sphericalshape. For example, the surface 103 of the base portion 101 may beformed into a polyhedron, and one lens receiving portion 104 may beprovided to each surface of the polyhedron.

Modified Example 1-1

Next, a modified example 1-1 of the first embodiment of the presentinvention will be described.

FIG. 6 is a cross-sectional view illustrating a structure of a lensholding tool according to the modified example 1-1. As illustrated inFIG. 6, the lens holding tool 120 according to the modified example 1-1includes a plurality of lens receiving portions 121 provided on thesurface 103 of the base portion 101. In FIG. 6, only one lens receivingportion 121 is illustrated in an enlarged scale. The structure of thebase portion 101 is the same as that of the first embodiment.

The lens receiving portion 121 includes cylindrical protrusion portions122 and 123 provided coaxially in a double ring shape. The outerdiameter of the protrusion portion 122 of the outermost periphery issubstantially the same as the outer diameter of the held lens 10. Lensreceiving faces 124 and 125, which are upper end faces of the protrusionportions 122 and 123, are in contact with the support surface 12 of thelens 10 and support the lens 10. In the modified example 1-1, the lensreceiving faces 124 and 125 have a concave spherical shape which has acommon spherical center on a rotation symmetry axis R2 of the outerprotrusion portion 122 and whose curvature radius is substantially thesame as that of the support surface 12.

The positions of the lens receiving faces 124 and 125 are not limited inparticular as long as an outer circumference 126 of the outer lensreceiving face 124 is located higher than the surface 103 of the baseportion 101. For example, the inner lens receiving face 125 may belocated lower than the surface 103 depending on the curvature radius ofthe support surface 12.

In this way, the cylindrical protrusion portion 123 is further providedinside the cylindrical protrusion portion 122 that supports theperipheral edge of the lens 10. Consequently, it is possible to stablysupport the lens 10 without causing deflection and the like in the lens10 even when the diameter of the lens 10 is large.

In the modified example 1-1, the lens receiving portion 121 is formed toinclude the double cylindrical protrusion portions 122 and 123. However,three or more cylindrical protrusion portions may be included. Further,a column-shaped protrusion portion may be provided instead of the innerprotrusion portion 123. In this case, the upper end face of theprotrusion portion having the column shape is formed into a concavespherical shape which has a spherical center shared with the lensreceiving face 124 of the outer protrusion portion 122 and whosecurvature radius is substantially the same as that of the supportsurface 12.

Modified Example 1-2

Next, a modified example 1-2 of the first embodiment of the presentinvention will be described.

FIG. 7 is a cross-sectional view illustrating a structure of a lensholding tool according to the modified Example 1-2. As illustrated inFIG. 7, the lens holding tool 130 according to the modified example 1-2includes a plurality of lens receiving portions 131 provided on thesurface of the base portion 101. In FIG. 7, only one lens receivingportion 131 is illustrated in an enlarged scale. The structure of thebase portion 101 is the same as that of the first embodiment.

The lens receiving portion 131 has a column shape whose outer diameteris substantially the same as that of the lens 10. A lens receiving face132, which is the upper end face of the lens receiving portion 131, isin contact with the support surface 12 of the lens 10 and supports thelens 10. In the modified example 1-2, the lens receiving face 132 has aconcave spherical shape which has a spherical center on a rotationsymmetry axis R3 of the outer circumferential surface of the lensreceiving portion 131 and whose curvature radius is substantially thesame as that of the support surface 12.

The position of the lens receiving face 132 is not limited in particularas long as an outer circumference 133 of the lens receiving face 132 islocated higher than the surface 103 of the base portion 101. Forexample, a central portion 134 of the lens receiving face 132 may belocated lower than the surface 103 depending on the diameter and thecurvature radius of the lens receiving face 132.

As described above, the lens receiving portion 131 is formed into acolumn shape. Consequently, it is possible to cause the lens receivingface 132 to be in contact with the entire support surface 12 as well asto stably hold the lens 10. Further, as the structure of the lensreceiving portion 131 is simple, it is possible to manufacture the lensholding tool 130 in a simple process.

Modified Example 1-3

Next, a modified example 1-3 of the first embodiment of the presentinvention will be described.

In the first embodiment described above, when attaching the lens 10 tothe lens holding tool 100, the adhesive 112 is cured in a state in whichthe ring 110 is fitted into the lens receiving portion 104. However, ifit is possible to prevent positional shift of the lens 10 with respectto the lens receiving portion 104, the ring 110 need not necessarily beused. For example, after the outer circumferences of the lens 10 and thelens receiving face 105 are positioned to be aligned to each other, theadhesive 112 may be cured in a state in which the lens 10 and the lensreceiving face 105 are held by hands so that they are not shifted fromeach other. Alternatively, a vacuum hole that opens in the lensreceiving face 105 is provided in the lens receiving portion 104 and thebase portion 101, and the vacuum hole is used for depressurization afterthe outer circumferences of the lens 10 and the lens receiving face 105are positioned to be aligned to each other, and thereby the lens 10 isvacuum-sucked to the lens receiving face 105. In this state, theadhesive 112 may be cured.

Second Embodiment

Next, a second embodiment of the present invention will be described.

FIG. 8 is a cross-sectional view illustrating structure of a lensholding tool according to the second embodiment of the presentinvention. As illustrated in FIG. 8, a lens holding tool 200 accordingto the second embodiment includes a base portion 201 and a pluralitylens receiving portions 104 which is provided so as to protrude from asurface 202 of the base portion 201. In FIG. 8, only one lens receivingportion 104 is illustrated in an enlarged scale.

The base portion 201 is a member made of metal or alloy, which forms apartial shape of a spherical body, in the same manner as the baseportion 101 illustrated in FIG. 1B. The surface 202 of the base portion201 forms a spherical shape, and a shaft portion (not illustrated in thedrawings) coaxial with the rotation center of the base portion 201 isprovided on a surface opposite to the surface 202.

The structure of the lens receiving portion 104 is basically the same asthat in the first embodiment. However, in the second embodiment, thelens receiving portion 104 causes the lens receiving face 105 to be incontact with a region inside the outer circumference of a supportsurface 22 of a lens 20, and holds the lens 20 whose diameter is greaterthan the outer diameter of the lens receiving portion 104.

An annular groove portion 203, which is coaxial with the lens receivingportion 104 and whose inner diameter is greater than the outer diameterof the lens receiving portion 104, is formed around each of the lensreceiving portions 104. As described later, the groove portion 203 isused to cause the lens receiving portion 104 to hold the lens 20.

FIG. 9 is a cross-sectional view for explaining a positioning step of alens holding method according to the second embodiment. In the secondembodiment, a ring 210 is used as an auxiliary support means to causethe lens receiving portion 104 to hold the lens 20. The ring 210 is acylindrical member whose inner diameter is substantially the same as anouter diameter D3 of the lens 20 and which can fit into the grooveportion 203. The ring 210 is fitted into the groove portion 203 so thata positioning surface of the lens 20, which is in parallel with arotation symmetry axis R1 of the lens receiving portion 104 and whosedistances from the rotation symmetry axis R1 are the same, is formedaround the lens receiving portion 104 by an inner circumferentialsurface 211 of the ring 210.

When causing the lens receiving portion 104 to hold the lens 20, anadhesive 212 such as wax or ultraviolet curing resin is applied to thelens receiving face 105 (or the support surface 22 of the lens 20).Then, the lens 20 is placed on the lens receiving face 105 with thesupport surface 22 of the lens 20 facing the lens receiving face 105,and the support surface 22 of the lens 20 and the lens receiving face105 are caused to be in contact with each other through the adhesive212.

Further, the ring 210 is fitted into the groove portion 203 by puttingthe ring 210 from above the lens 20, and the outer circumferentialsurface of the lens 20 is caused to be in contact with the innercircumferential surface 211 of the ring 210. Thereby, the positioning ofthe lens 20 is performed with respect to the lens receiving portion 104.After the adhesive 212 is cured in this state, the ring 210 is removed.Thereby, it is possible to obtain the lens holding tool 200 in which thelens 20 is held in an appropriate position.

As described above, according to the second embodiment, it is possibleto process the lens 20 by causing the lens receiving portion 104 to holdthe lens 20 whose diameter is greater than the outer diameter of thelens receiving portion 104.

Instead of the lens receiving portion 104, the lens receiving portion121 in the modified example 1-1 or the lens receiving portion 131 in themodified example 1-2 may be employed in the second embodiment.

Third Embodiment

Next, a third embodiment of the present invention will be described.

In FIG. 10, (a) is a top view illustrating a structure of a lens holdingtool according to a third embodiment of the present invention, and (b)is a B-B cross-sectional view of (a). As illustrated in FIG. 10, a lensholding tool 300 according to the third embodiment includes a baseportion 301 and a plurality of lens receiving portions 104 which isprovided so as to protrude from a surface 302 of the base portion 301.In FIG. 10, only one lens receiving portion 104 is illustrated in anenlarged scale.

The base portion 301 is a member made of metal or alloy, which forms apartial shape of a spherical body, in the same manner as the baseportion 101 illustrated in FIG. 1B. The surface 302 of the base portion301 forms a spherical shape, and a shaft portion (not illustrated in thedrawings) coaxial with the rotation center of the base portion 301 isprovided on a surface opposite to the surface 302.

The structure of the lens receiving portion 104 is the same as that ofthe first embodiment. On the surface 302 around each of the lensreceiving portions 104, a pin hole 303 is formed in at least threepositions along the outer circumference of the lens receiving portion104. As described later, the pin hole 303 is used to cause the lensreceiving portion 104 to hold the lens 10. It is preferable to arrangethe pin holes 303 as uniformly as possible. In FIG. 10, three pin holes303 are arranged to be threefold rotation symmetrical with respect tothe rotation symmetry axis R1.

In FIG. 11, (a) is a top view for explaining a positioning step of alens holding method according to the third embodiment, and (b) is a B-Bcross-sectional view of (a). In the third embodiment, at least threepins 304 are used as an auxiliary support means to cause the lensreceiving portion 104 to hold the lens 10. Each pin 304 is a memberhaving a pillar shape (for example, column shape). Each pin 304 can befitted into the pin hole 303. By fitting these pins 304 into the pinholes 303, positioning markers 305 of the lens 10, which are in parallelwith the rotation symmetry axis R1 of the lens receiving portion 104 andwhose distances from the rotation symmetry axis R1 are the same, areformed in at least three positions around the lens receiving portion104.

When causing the lens receiving portion 104 to hold the lens 10, anadhesive 306 is applied to a lens receiving face 105 (or a supportsurface 12 of the lens 10). Then, the lens 10 is placed on the lensreceiving face 105 with the support surface 12 of the lens 10 facing thelens receiving face 105, and the support surface 12 of the lens 10 andthe lens receiving face 105 are caused to be in contact with each otherthrough the adhesive 306. Further, the pins 304 are inserted into thepin holes 303 and the outer circumferential surface of the lens 10 iscaused be in contact with the side surface of each pin 304, and therebythe positioning of the lens 10 is performed with respect to the lensreceiving portion 104. After the adhesive 306 is cured in this state,the pins 304 are removed. Thereby, it is possible to obtain the lensholding tool 300 in which the lens 10 is held in an appropriateposition.

As described above, according to the third embodiment, it is possible toperform the positioning of the lens 10 with a simple configuration.

Further, it is possible to cause the lens receiving portion 104 to holda lens whose diameter is greater than the outer diameter of the lensreceiving portion 104 by arranging three or more pin holes 303 along acircle which is coaxial with the outer circumference 106 of the lensreceiving portion 104 and whose diameter is greater than the diameter ofthe outer circumference 106. Instead of the lens receiving portion 104,the lens receiving portion 121 in the modified example 1-1 or the lensreceiving portion 131 in the modified example 1-2 may be employed in thethird embodiment.

Fourth Embodiment

Next, a fourth embodiment of the present invention will be described.

In FIG. 12, (a) is a top view illustrating a structure of a lens holdingtool according to a fourth embodiment of the present invention, and (b)is a C-C cross-sectional view of (a). As illustrated in FIG. 12, a lensholding tool 400 according to the fourth embodiment includes a baseportion 401 and a plurality of lens receiving portions 104 which isprovided so as to protrude from a surface 402 of the base portion 401.In FIG. 12, only one lens receiving portion 104 is illustrated in anenlarged scale.

The base portion 401 is a member made of metal or alloy, which forms apartial shape of a spherical body, in the same manner as the baseportion 101 illustrated in FIG. 1B. The surface 402 of the base portion401 forms a spherical shape, and a shaft portion (not illustrated in thedrawings) coaxial with the rotation center of the base portion 401 isprovided on a surface opposite to the surface 402.

The structure of the lens receiving portion 104 is the same as that ofthe first embodiment. A groove portion 403 is formed at a predeterminedposition near each of the lens receiving portions 104. As describedlater, the groove portion 403 is used to cause the lens receivingportion 104 to hold a lens 10.

In FIG. 13, (a) is a top view for explaining a positioning step of alens holding method according to the fourth embodiment, and (b) is a C-Ccross-sectional view of (a). In the fourth embodiment, a V-shaped jig404 is used as an auxiliary support means to cause the lens receivingportion 104 to hold the lens 10, The V-shaped jig 404 includes a mainbody portion 406 provided with two flat surfaces 405 crossing in a Vshape, and a leg portion 407 which supports the main body portion 406and which can be fitted into the groove portion 403. The leg portion 407is fitted into the groove portion 403, and thereby a positioning surfacewhere the outer circumferential surface of the lens 10 can be in contactwith at two positions which are in parallel with a rotation symmetryaxis R1 of the lens receiving portion 104 and whose distances from therotation symmetry axis R1 are the same, is formed by the two flatsurfaces 405 in the vicinity of the lens receiving portion 104.

When causing the lens receiving portion 104 to hold the lens 10, anadhesive 408 is applied to a lens receiving face 105 (or a supportsurface 12 of the lens 10). Then, the lens 10 is placed on the lensreceiving face 105 with the support surface 12 of the lens 10 facing thelens receiving face 105. The support surface 12 of the lens 10 and thelens receiving face 105 are, then, caused to be in contact with eachother through the adhesive 408. Further, the leg portion 407 of theV-shaped jig 404 is inserted into the groove portion 403, and an outercircumference 13 of the lens 10 is caused to be in contact with the twoflat surfaces 405. Thereby, the positioning of the lens 10 is performedwith respect to the lens receiving portion 104. After the adhesive 408is cured in this state, the V-shaped jig 404 is removed. Thereby, it ispossible to obtain the lens holding tool 400 in which the lens 10 isheld in an appropriate position.

As described above, according to the fourth embodiment, it is possibleto easily perform the positioning of the lens 10.

It is also possible to cause the lens receiving portion 104 to hold alens whose diameter is greater than the outer diameter of the lensreceiving portion 104 by changing the position of the two flat surfaces405 which form the V-shaped jig 404, and/or the angle at which the flatsurfaces 405 cross each other. In this case, it is possible to cope withpositioning of various lenses whose diameters are different from eachother by only changing the V-shaped jig 404 inserted into the grooveportion 403. Further, instead of the lens receiving portion 104, thelens receiving portion 121 in the modified example 1-1 the lensreceiving portion 131 in the modified example 1-2 may be employed in thefourth embodiment.

Fifth Embodiment

Next, a fifth embodiment of the present invention will be described.

FIG. 14 is a cross-sectional view illustrating a structure of a lensholding tool according to the fifth embodiment of the present invention.As illustrated in FIG. 14, s lens holding tool 500 according to thefifth embodiment includes a base portion 501 and a plurality of lensreceiving portions 510 which is provided so as to protrude from asurface 503 of the base portion 501. FIG. 14 illustrates a state inwhich a lens 50 as a workpiece is held by each of the lens receivingportions 510 through an adhesive 520. FIG. 14 illustrates, as anexample, a cross-section (a cross-section corresponding to the line A-Ain FIG. 1A) in a case in which seven lens receiving portions 510 areprovided in the same arrangement as that in FIG. 1A. However, the numberof the lens receiving portions 510 only has to be three or more.

The base portion 501 is a member made of metal or alloy, which forms apartial shape of a spherical body. A shaft portion 502 coaxial with therotation center of the base portion 501 is provided on a surfaceopposite to the surface 503 which forms a concave spherical shape. Acolumn-shaped counterbore hole 504 is formed at a plurality of positionsin the surface 503 and a female screw hole 505 is formed in the bottomsurface of each counterbore hole 504.

FIG. 15 is a partial cross-sectional view illustrating the lensreceiving portion 510 in an enlarged scale. The lens receiving portion510 is configured to be attached to and detached from the base portion501. The lens receiving portion 510 includes a column portion 511 whoseouter diameter is substantially the same as an outer diameter D4 of thelens 50 and a male screw portion 512 which is provided on the bottomportion of the column portion 511 and can be screwed with the femalescrew hole 505.

A lens receiving face 513 is an upper end face of the column portion511. The lens receiving face 513 is in contact with a support surface52, which is an end face opposite to a process surface 51 of the lens50, and supports the lens 50. In the fifth embodiment, corresponding tothe support surface 52 of the convex spherical shape, the lens receivingface 513 has a concave spherical shape which has a spherical center on arotation symmetry axis R4 of the outer circumferential surface of thecolumn portion 511 and whose curvature radius is substantially the sameas that of the support surface 52.

The height of the column portion 511 is set so that an outercircumference 514 of the lens receiving face 513 is higher than thesurface 503 of the base portion 501 when the lens receiving portion 510is attached to the base portion 501, based on a relationship with thedepth of the counterbore hole 504 formed in the base portion 501.Thereby, it is possible to prevent a processing tool such as agrindstone from being in contact with the base portion 501 duringprocessing of the lens 50, regardless of the thickness of an edgeportion of the lens 50. The height of a central portion 515 of the lensreceiving face 513 is determined by the diameter and the height of theouter circumference 514 and the curvature radius of the lens receivingface 513. Therefore, when the lens receiving portion 510 is attached tothe base portion 501, the height of the central portion 515 may be lowerthan the surface 503.

FIG. 16 is a partial cross-sectional view for explaining an adhesiveapplication step, a lens placement step, and a positioning step of alens holding method according to the fifth embodiment. FIG. 17 is apartial cross-sectional view for explaining a lens receiving portionattaching step of the lens holding method.

First, as illustrated in FIG. 16, when the lens receiving portion 510 isdetached from the base portion 501, the adhesive 520 is applied to thelens receiving face 513 (or the support surface 52 of the lens 50).Subsequently, the lens 50 is placed on the lens receiving face 513 withthe support surface 52 of the lens 50 facing the lens receiving face513, the support surface 52 of the lens 50 and the lens receiving face513 are caused to be in contact with each other through the adhesive520, and positioning of the outer circumferences of the lens 50 and thelens receiving face 513 is performed. In this step, the positioning maybe performed by fitting a ring whose inner diameter is substantially thesame as the outer diameter of the lens receiving face 513 (that is, theouter diameter D4 of the lens 50) to the column portion 511 and the lens50, in the same manner as in the first embodiment. Then, the adhesive520 is cured in this state.

Subsequently, as illustrated in FIG. 17, the lens receiving portion 510to which the lens 50 is attached is inserted into each counterbore hole504 of the base portion 501, and the male screw portion 512 is screwedinto the female screw hole 505. Thereby, it is possible to obtain thelens holding tool 500 in which the lenses 50 are held in appropriatepositions (see FIG. 14).

As described above, according to the fifth embodiment, the lensreceiving portion 510 can be attached to and detached from the baseportion 501. Consequently, it is possible to easily perform an operationto attach the lens 50 to the lens receiving portion 510. In particular,the lens 50 is attached in a state in which the axis of the lensreceiving portion 510 is oriented in the vertical direction. Thereby, itis possible to suppress positional shift of the lens 50 during a perioduntil the adhesive 520 is cured.

Further, in the fifth embodiment, the surface 503 of the base portion501 is formed into a concave spherical shape so that a plurality of lensreceiving faces 513 is arranged in a concave shape in order to grind orpolish the process surface 51 of the lens 50 into a concave sphericalshape. However, when grinding or polishing the process surface 51 of thelens 50 into a convex spherical shape, it is preferable to form thesurface 503 of the base portion 501 into a convex spherical shape sothat a plurality of the lens receiving faces 513 is arranged in a convexshape. Further, when a plurality of the lens receiving faces 513 isarranged corresponding to a processed shape (the curvature) of theprocess surface 51, the shape of the surface 503 of the base portion 501is not particularly limited and need not necessarily be a sphericalshape.

Also in the fifth embodiment, in the same manner as in the firstembodiment and the modified example 1-1, the lens 50 may be supported byan end face including one or more ring-shaped surfaces.

Modified Example 5-1

Next, a modified example 5-1 of the fifth embodiment of the presentinvention will be described.

In the fifth embodiment described above, the lens receiving portion 510is fixed to the base portion 501 by screwing the male screw portion 512into the female screw hole 505. However, the fixing means is not limitedto this.

For example, as illustrated in FIG. 18, a lens receiving portion 530 maybe formed of a column-shaped member where a lens receiving face 531,which is an upper end face that can be in contact with the supportsurface 52 of the lens 50, is provided. FIG. 18 illustrates a state inwhich the lens 50 is attached to the lens receiving face 531 by theadhesive 520. In this way, when no screw portion is provided to the lensreceiving portion 530, the lens receiving portion 530 may be fixed tothe counterbore hole 504 (see FIG. 17) by using an adhesive.Accordingly, it is also possible to attach the lens receiving portion530 to a conventional recessed plate where only a counterbore hole isprovided in the surface of the base portion. Alternatively, an engagingmeans is provided to the lens receiving portion 530 and the counterborehole 504, and the lens receiving portion 530 and the counterbore hole504 may be mechanically fixed.

According to some embodiments, the lens receiving portion is provided soas to protrude from the surface of the base portion. Because a lens as aworkpiece is held such that one end face of the lens is in contact withthe lens receiving face, it is possible to secure a sufficient clearancebetween the surface of the base portion and the processing tool. Withthis structure, it is possible to cause the lens holding tool to hold aplurality of lenses as a workpiece and perform a grinding or polishingprocess at the same time regardless of the shape of the lenses.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A lens holding tool for holding a plurality oflenses as a workpiece in a grinding or polishing process, the lensholding tool comprising: a base portion; and a plurality of lensreceiving portions respectively provided at a plurality of positions ona surface of the base portion so as to protrude from the surface,wherein each of the plurality of lens receiving portions has a lensreceiving face configured to be in contact with at least a part of asupport surface which is an end face of each of the plurality of lenses,and an outer circumference of the lens receiving face is positionedhigher than the surface of the base portion.
 2. The lens holding toolaccording to claim 1, wherein each of the plurality of lens receivingportions has at least a single cylindrical shape whose upper end face isthe lens receiving face.
 3. The lens holding tool according to claim 1,wherein each of the plurality of lens receiving portions has a columnshape whose upper end face is the lens receiving face.
 4. The lensholding tool according to claim 1, wherein each of the plurality of lensreceiving portions has: a first protrusion portion having a column shapewhose upper end face is the lens receiving face; and a second protrusionportion having at least a single cylindrical shape whose upper end faceis the lens receiving face and which is provided outside of an outercircumference of the first protrusion portion.
 5. The lens holding toolaccording to claim 1, wherein at least three lens receiving portions areprovided as the plurality of lens receiving portions.
 6. The lensholding tool according to claim 1, wherein each of the plurality of lensreceiving portions is integrated with the base portion.
 7. The lensholding tool according to claim 1, wherein each of the plurality of lensreceiving portions is configured to be attached to and detached from thebase portion.
 8. The lens holding tool according to claim 1, wherein anouter diameter of each of the plurality of lens receiving portions isequal to an outer diameter of the lens receiving face.
 9. A method forcausing a lens holding tool to hold a plurality of lenses as a workpiecein a grinding or polishing process, the lens holding tool having a baseportion and a plurality of lens receiving portions on the base portion,each of the plurality of lens receiving portions having a lens receivingface, the method comprising: applying an adhesive to at least one of thelens receiving face and a support surface which is an end face of eachof the plurality of lenses; placing each of the plurality of lenses onthe lens receiving face to cause the support surface and the lensreceiving face to be in contact with each other through the adhesive;positioning each of the plurality of lenses with respect to each of thelens receiving portions; and curing the adhesive, wherein each of thelens receiving portions protrudes from a surface of the base portion,and an outer circumference of the lens receiving face is positionedhigher than the surface of the base portion.
 10. The method according toclaim 9, wherein the positioning of each of the plurality of lensescomprises attaching a support unit to the lens holding tool, wherein thesupport unit is configured to be attached to and detached from the lensholding tool, and when the support unit is attached to the lens holdingtool, a positioning marker or a positioning surface with which an outercircumferential surface of each of the plurality of lenses is configuredto be in contact is formed in at least two positions which are inparallel with a rotation symmetry axis of each of the plurality of lensreceiving portions and whose distances from the rotation symmetry axisare the same, and the support unit is removed after curing the adhesive.11. The method according to claim 10, wherein the support unit is acylindrical member having an inner circumferential surface configured tobe in contact with the outer circumferential surface of each of theplurality of lenses.
 12. The method according to claim 9, wherein eachof the plurality of lens receiving portions is configured to be attachedto and detached from the base portion, and the method further comprisesattaching each of the plurality of lens receiving portions which adheresto each of the plurality of lenses, to the base portion after curing theadhesive.
 13. The method according to claim 9, wherein each of theplurality of lenses has a process surface configured to be processed,and the process surface is positioned higher than the outercircumference of the lens receiving face.
 14. The method according toclaim 9, wherein an outer diameter of each of the plurality of lenses isequal to or greater than an outer diameter of each of the plurality oflens receiving portions.